'\" et
.TH ULIMIT "1P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
ulimit
\(em set or report file size limit
.SH SYNOPSIS
.LP
.nf
ulimit \fB[\fR-f\fB] [\fIblocks\fB]\fR
.fi
.SH DESCRIPTION
The
.IR ulimit
utility shall set or report the file-size writing limit imposed on
files written by the shell and its child processes (files of any size
may be read). Only a process with appropriate privileges can increase
the limit.
.SH OPTIONS
The
.IR ulimit
utility shall conform to the Base Definitions volume of POSIX.1\(hy2017,
.IR "Section 12.2" ", " "Utility Syntax Guidelines".
.P
The following option shall be supported:
.IP "\fB\-f\fP" 10
Set (or report, if no
.IR blocks
operand is present), the file size limit in blocks. The
.BR \-f
option shall also be the default case.
.SH OPERANDS
The following operand shall be supported:
.IP "\fIblocks\fR" 10
The number of 512-byte blocks to use as the new file size limit.
.SH STDIN
Not used.
.SH "INPUT FILES"
None.
.SH "ENVIRONMENT VARIABLES"
The following environment variables shall affect the execution of
.IR ulimit :
.IP "\fILANG\fP" 10
Provide a default value for the internationalization variables that are
unset or null. (See the Base Definitions volume of POSIX.1\(hy2017,
.IR "Section 8.2" ", " "Internationalization Variables"
for the precedence of internationalization variables used to determine
the values of locale categories.)
.IP "\fILC_ALL\fP" 10
If set to a non-empty string value, override the values of all the
other internationalization variables.
.IP "\fILC_CTYPE\fP" 10
Determine the locale for the interpretation of sequences of bytes of
text data as characters (for example, single-byte as opposed to
multi-byte characters in arguments).
.IP "\fILC_MESSAGES\fP" 10
.br
Determine the locale that should be used to affect the format and
contents of diagnostic messages written to standard error.
.IP "\fINLSPATH\fP" 10
Determine the location of message catalogs for the processing of
.IR LC_MESSAGES .
.SH "ASYNCHRONOUS EVENTS"
Default.
.SH STDOUT
The standard output shall be used when no
.IR blocks
operand is present. If the current number of blocks is limited, the
number of blocks in the current limit shall be written in the following
format:
.sp
.RS 4
.nf

"%d\en", <\fInumber of 512-byte blocks\fR>
.fi
.P
.RE
.P
If there is no current limit on the number of blocks, in the POSIX
locale the following format shall be used:
.sp
.RS 4
.nf

"unlimited\en"
.fi
.P
.RE
.SH STDERR
The standard error shall be used only for diagnostic messages.
.SH "OUTPUT FILES"
None.
.SH "EXTENDED DESCRIPTION"
None.
.SH "EXIT STATUS"
The following exit values shall be returned:
.IP "\00" 6
Successful completion.
.IP >0 6
A request for a higher limit was rejected or an error occurred.
.SH "CONSEQUENCES OF ERRORS"
Default.
.LP
.IR "The following sections are informative."
.SH "APPLICATION USAGE"
Since
.IR ulimit
affects the current shell execution environment, it is always provided
as a shell regular built-in. If it is called in a separate utility
execution environment, such as one of the following:
.sp
.RS 4
.nf

nohup ulimit -f 10000
env ulimit 10000
.fi
.P
.RE
.P
it does not affect the file size limit of the caller's environment.
.P
Once a limit has been decreased by a process, it cannot be increased
(unless appropriate privileges are involved), even back to the original
system limit.
.SH EXAMPLES
Set the file size limit to 51\|200 bytes:
.sp
.RS 4
.nf

ulimit -f 100
.fi
.P
.RE
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
The Base Definitions volume of POSIX.1\(hy2017,
.IR "Chapter 8" ", " "Environment Variables",
.IR "Section 12.2" ", " "Utility Syntax Guidelines"
.P
The System Interfaces volume of POSIX.1\(hy2017,
.IR "\fIulimit\fR\^(\|)"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
